Comment Form Missing

For some reason the comment form is missing on one of my blog posts. But it shows up on all other blog posts. Under PageLines Section Control I do not have the Hide Comment Form box enabled. Any ideas on what might be causing this error to prevent the comment box from showing on this post? The post page with the problem is here:

http://marcschultz.com/blog/best-way-light-white-studio-backdrop/

Cheers…